The Australian Communications and Media Authority investigated the interview, aired on August 22, in which Sales grilled Mr Abbott over his claim that BHP had suspended its Olympic Dam project because of the carbon tax.

Ms Sales extracted an admission from Mr Abbott that he had not read BHP's statement, which made no mention of the tax.

The timing could not be worse for the Opposition Leader, who is now under attack for failing to read a Federal Court judgment dismissing the sexual harassment case against the former the parliamentary Speaker, Peter Slipper.

The probe into 7.30 was sparked by two complaints. One claimed that Sales' treatment of Mr Abbott ''was very bad … she made it obvious that she does not like him''.

Another stated that Sales' ''personal left-wing views are showing through … I also believe the ABC is responsible for a great deal of left-wing bias''.

In response, the ABC told ACMA that Sales had used a ''devil's advocate'' style and that it did ''not believe that posing testing questions to an interviewee and then allowing them to respond to those questions is biased or bad-mannered. It is, in fact, a recognised standard of objective journalism''.